The present invention relates to a sheet stacking arrangement for stacking up or piling up sheets, for example, paper sheets discharged from a recording apparatus such as a copying machine and the like, by turning over such paper sheets as they are discharged.
Conventionally, in the recording apparatuses such as copying machines, etc., it has generally been so arranged that paper sheets are discharged, with the recorded surfaces thereof directed upwards, while, for the sheet stacking arrangements provided as auxiliaries to the recording apparatuses of this kind, there have been proposed the so-called face-up system in which the paper sheets are fed in a generally horizontal direction, with their recorded surfaces directed upwards so as to be piled up as they are, and the so-called face-down system in which the paper sheets are turned over so as to be stacked up with their recorded surfaces directed downwards. However, in the former system, the paper sheets are consequently stacked up in the order opposite to that in which they are recorded and, for example, in the case where copying is started from a first page of original documents to be copied, it has been necessary to rearrange the order of pages by exchanging upper sheets with lower sheets, one by one, in the stack of copied paper sheets taken out from the sheet stacking arrangement. Meanwhile, in the latter system of the paper sheet turning-over type, although the copy paper sheets are turned over during processing, they are consequently stacked up normally in the order of pages, without necessity for the rearrangement of the paper sheets as in the former system.
On the other hand, it is convenient to employ a sorter for the classification of paper sheets discharged from the recording apparatus, but in this case, the sorter itself is of a large scale, requiring a high cost for installation. Accordingly, there has been proposed a recording apparatus equipped with a simplified classification mechanism which is arranged to stack up paper sheets by laterally shifting a sheet discharge tray after copying of a predetermined number of sheets in such a manner as to form steps in the lateral direction.
Incidentally, for classifying paper sheets through employment of the classification mechanism as described above, it is desirable that the respective paper sheets be accommodated in the paper discharge tray with the leading edges of said sheets being correctly aligned, and thus, a high accuracy in stacking is required.
In the conventional sheet stacking arrangements, however, it has been impossible to stack up the sheets with the leading edges thereof correctly aligned, the arrangement being very poor in stacking accuracy, and even when the classification mechanism has been employed, it has not been very convenient to use.